DESCRIPTION (Adapted from applicant's description): This is an application for continued participation as one of the Clinical Units in an extended Collaborative Home Infant Monitoring Evaluation (CHIME) Study over the next five years. Each year, approximately 50,000 infants are placed on a home cardiorespiratory (CR) monitor. Monitors are typically prescribed for infants in one of three groups at increased risk for Sudden Infant Death Syndrome (SIDS): infants who experience an idiopathic apparent life-threatening event (apnea of infancy, AO1), SIDS siblings, and preterm infants. Despite years of experience, it is not known to what extent monitor use has reduced either infant morbidity or mortality. The CHIME study is designed to address the unresolved questions regarding who has CR events at home, the nature of these events, and their impact on neurodevelopmental outcome. We propose a 5-year extension of the CHIME study in order to complete enrollment, follow-up, and data analysis. A total of 2,115 infants will be enrolled: 375 healthy term infants, 330 SIDS siblings, 330 with AO1, and 1,080 preterm infants < 1750 g birth weight. Each infant will receive an overnight polysonogram and will be monitored at home for 4-5 months using a memory monitor developed for the CHIME study. The monitor will store all CR events occurring at home and the associated oxygen saturation and sleep position, will record periodic non-event (normative) intervals, and will continuously record R-R and breath-to-breath intervals. Apneas will be categorized as central, mixed or obstructive by the use of inductance plethysmography, a technique not previously available for home monitoring. Clinical and neurodevelopmental status will be ascertained longitudinally through 1 year of age. The CHIME study will create a comprehensive summary of the full range of CR events occurring in the home. The results will yield important insights regarding underlying mechanisms, antecedent variables predictive of events, appropriate intervention strategies, and the relationship between CR events and neurodevelopmental out-come.